Many machines include motion-control systems that have one or more moveable components and controls that regulate the motion of the one or more moveable components. Some such motion-control systems include an operator interface with a moveable operator-input member, such as a joystick, steering wheel, or a pedal, that an operator may use to provide input to the motion-control system. In some cases, such an operator-input member may provide inputs to one or more components of the motion-control system through a mechanical connection. Such a mechanical connection between an operator-input member and another component of the motion-control system may transmit feedback forces to the operator-input member. An operator may glean information about the operation of the motion-control system from such feedback forces.
Some motion-control systems use means other than a mechanical connection to transmit inputs from a moveable operator-input member to one or more other components of the motion-control system. For example, some motion-control systems may use electrical signals to transmit operator inputs received through an operator-input member to other components of the motion-control system. Such other means of transmitting operator inputs to other components of the motion-control system may have various advantages, but they generally do not provide feedback force to the operator manipulating the operator-input member.
U.S. Pat. No. 6,535,806 B2 to Millsap et al. (“the '806 patent”) discloses a steer-by-wire type steering system with a steering wheel tactile feedback device that provides feedback force on the steering wheel of the steering system. The steering system of the '806 patent includes a controller that supplies the steering wheel tactile feedback device with a command signal that controls the magnitude of the feedback force that the steering wheel tactile feedback device applies to the steering wheel. The controller generates the command signal based on the speed of the vehicle, the actual steering direction of the vehicle, the angle of the steering wheel, and a control error determined by comparing an actual steering direction of the vehicle and the angle of the steering wheel. With reference to a block diagram in FIG. 2, the '806 patent describes one general signal-processing method that the controller may use to generate the command signal for the steering wheel tactile feedback device based on these factors.
Although the '806 patent discloses a steer-by-wire system with a steering wheel tactile feedback device that provides feedback force on the steering wheel of the steering system, certain disadvantages persist. For example, by using only speed and error as factors in controlling the magnitude of the feedback force, the steering system of the '806 patent may provide an operator only very basic information. As a result, the operator may not get all the information that the operator desires from the feedback force on the steering wheel. Additionally, the '806 patent does not disclose how the feedback force on the steering wheel actually varies as a function of the various factors that the controller uses to generate the command signal. If the controller does not maintain a desirable relationship between these factors and the feedback force on the steering wheel, it may compromise the operating experience for the operator of the vehicle.
The motion-control system and methods of the present disclosure solve one or more of the problems set forth above.